Variable reactor



P 1935- w. a. NAGEL El AL I 2,013,106

VARIABLE REACTOR Filed March 2, 1934 UNITED STATES PATENT OFFICE VARIABLE REALTOR William G. Nagel'and Luther Ii. Seviaon, Toledo. Ohio; said BeviacnaaaignortoaaidNagol Month! March 2, 1934, Serial No. 718,740

1 Claim. (Cl. 171-242) This invention relates to liquid lev indicators made of any suitable metal, but is preferably of and more particularly to that class of oat operbrass or other non-magnetic material. On the ated devices in which a remote indication is made upper end of the stem, in the present instance, by an electric meter. is fixed a Plunger I which is made of magnetic 5 In adapting float operated electric indicators material, and which comprises a central cylin- 5 for use with fuel oil tanks or similarly volatile drical portion of a length approximately equal and viscous liquids, it has been found that the to one-half of the length of the system in which fumes given of! by the liquid cause a sticky deit operates. The plunger constitutes an armaposit to form on the relatively movable parts of ture and is preferably rolled about the stem 2 the indicator. This condition results is defective so as to leave a narrow air gap 4. operation, and in the case of indicators in when A double solenoid or reactance device is proa contact is moved by the float over a resistance vided and comprise an D m i body coil, may so impair the electrical connection at 5 having cylindrical holes 0 formed in each arm. this point as to render the indicator useless. For Between the arms, a pair of similar reactance this reason, oil level indicators have been concoils i and I are held, so that the magnetic cir- 15 flned largely to the mechanical type. These cuits of the two are closely coupled. The coils indicators must necessarily be located at or near have a common connection 9' between the windthe tank itself so that their utility is slight commas. and independent end connections 9" and 8. pared to one which is located remote from the Obviously, the er 0! tu n a d size 01' the 90 tank at any point which the user desires. Furwire in these coils may be varied to suit the re- 50 ther, the fumes from the oil have a decided corq i ments of the indicator. rosive efiect on the steel parts of such an instru- In operation, the armature i is moved into ment, so that the accuracy is so badly impaired and out of the bore of the reactance device in in a short time that the indicator is unreliable response to the movement of the float. A spring and useless. III is provided to calibrate the amplitude of move- 25 The present invention has for its primary obment impa to the armature y reason 0! a ject the provision of an indicator of the characincreased buoyan fo exerted y the float 88 ter described which is free from moving contacts the liquid level rises, so that the armature moves and the like that are apt to become inemcient in rou h he pr p r r ns Obviously this f c operation over a period of time. will be negative for a distance when the buoyant Another object of the invention is to provide force of the float is less than the weight of the such an indicator which is simple and inexfloat. stem and plunger. For this reason, the pensive to manufacture, readily installed, and caspring III is fixed to an adjustable collar III- at pable of standing continued use overalong period its lower end, so that it will resist downward of time, movement of the system as well as upward move- Other objects and advantages of the invention ment. will become apparent as the description proceeds, The position of the armature I determines the reference being bad to the accompanying drawquadrature component of the alternating curing, in which- I rent flowing in the coils I and 0, since the per- Figure 1 is a diagrammatic view, with parts meability of the magnetic circuit of each coil in section, of a preferred form of the device; depends on the position of the armature. In Fig. 2 is an elevation of the reluctance device used order to reduce the sharpness of the response to in Fig. 1; Fig. 3 is an enlarged view of one form a change in position, the plunger is tapered for a of the armature; and Fig. 4 is an equivalent cirdistance adjacent each of its ends as at H and cult diagram. ii. The air gap 4 reduces hysteresis losses in Referring to the drawing, l designates a float, the armature and so reduces the temperature at which in this instance, is a hollow cylindrical which the system operates. This is important if body closed on both ends and attached at its the indicator is to be used in connection with upper end to a stem i. Obviously the buoyant volatile inflammable liquids.

force exerted by the float member will be deter The measuring instrument provided may be mined by the degree of immersion and conseany two coil instrument in which common armaquently the level of liquid-in the tank. In some ture carries the vane and is moved with relation instances it may be advantageous to employ to the two coils by the magnetic influence of a small float pivoted within the tank to iollow both. One end of one coil is electrically conu the surface of the liquid. The stem 2 may be nected to an end of the other so as to provide a common point between the two. Such an instrument is shown at 20, but in itsel! comprises no part of the present invention. The instrument consists of two coils 2| and I! mounted in a suitable housing 23. An armature 24 is acted upon by the coils according to changes in their relative field strength. The armature is pivotally mounted by an arm-2i, which latter carries an indicating vane 28.

The circuit diagram shown in Fig. 4 discloses the preferred manner in which the device is operated. Coils A and B are the coils 2i and 22 01 the measuring instrument acting on the common armature 24. Coils C and D are the coils I and 8 01' the reactance device. 8 indicates a source of alternating current which is impressed across the bridge circuit so that one coil 01' the instrument and one of the reactance coils are in the same branch. It will be seen that a slight variation in frequency or voltage of the source will have no eflect from a practical standpoint on the response of the vane, since the change in the two branches would be substantially equal, and would not greatly affect the differential current caused by a change in position of the plunger dependent on the level 01' the liquid. Thus, so long as the frequency in the two branches is the same, a change in the inductance of one coil is counteracted to a sumclent extent to meet commercial requirements by a change in inductance 'intheothercoihsothatanychangeinthedii- Ierential reading is negligible. Voltage fluctuations are similarly unimportant.

We do not wish to be restricted to a float as the means responsive to variation in the liquid level, as the stem and armature may be motivated by any known pressure responsive device.

Obviously, various other modifications and changes may be made in the form and arrangement of the parts, and we wish it expressly understood that we are not limited to the specific construction shown, but include all forms within the scope or the appended claim.

Having thus described our invention, what we claim as new, and desire to secure by United States Letters Patent, is:

In an indicator, 9. variable reactor comprising two spaced reactance coils having their axes aligned, and E-shaped magnetic body having the central extension between said coils and each oi the outer extensions across an end of one oi the coils, each 0! said extensions having a hole aligned with the axes of said coils, and an armature movable axially in said coils.

LUTHER E. SEVISON. WILLIAM G. NAGEL. 

